Edward’s syndrome is a genetic defect that results in several abnormalities in the body of the babies born with condition. Babies with this chromosomal condition die soon after birth. There is no cure for the condition. It is also known as Trisomy 18 and affects one in five thousand live births. The possibility of a woman giving birth to a child with Edward's syndrome increases with the age of the pregnant woman.
While the condition is caused by a defect in chromosomes, it is not an inherited disease. In trisomy 18, the baby has three copies of chromosome number 18 instead of the requisite two. The error usually occurs during production of the sperm or the egg. It affects the normal growth of the baby. In 90% of the cases the defect has been attributed to the egg. The error occurs in cell division and is known as meiotic disjunction.
This is the most severe form of the condition. The baby will die shortly after being born. The baby usually has multiple defects and organ abnormalities such as a small misshapen head, a smaller-than-average jaw, clenched fists with overlapping fingers, low-set ears and exomphalos (this is when the intestines are found in a sac outside the stomach). There may be issues with the development of the heart, lungs and spinal column as well. These babies do not survive beyond the first month after birth.
Mosaic Trisomy 18
A slightly less severe form of the condition, in mosaic trisomy 18 only some cells of the baby have an extra copy of chromosome 18. Depending on the number and type of cells affected, the disabilities will differ from baby to baby. About seven in ten babies with this condition may survive a year or more. In rare cases, where the disabilities are not very pronounced, the individual may survive into early adulthood, but will never be able to function independently.
Partial Trisomy 18
This is the least severe form of the condition. In partial trisomy 18 only a section of the additional chromosome 18 is present rather than the entire additional chromosome. The severity of the baby’s disabilities will depend on the part of the chromosome present in the cells, as well as the number of cells which have the chromosomal defect. Partial trisomy 18 can be inherited when a parent carries a rearrangement of genetic material between two chromosomes, called a balanced translocation.
Diagnosing Edward's Syndrome
Screening for Edward’s syndrome occurs between 10 to 14 weeks of pregnancy. The combined test checks for Down’s syndrome and Patau’s syndrome as well. Those found to be at high risk after the combined test will be advised to undergo a diagnostic test to confirm the presence of Edward's syndrome. This is done by checking the baby’s cells for an extra copy of chromosome 18.
The two ways of obtaining the cell samples include chorionic villus sampling and amniocentesis. In chorionic villus sampling cells are collected from the placenta, or the tissue which connects the fetus to the mother. In amniocentesis a sample of the amniotic fluid in the womb around the baby is collected. This fluid contains the cells that the fetus has shed, and which are studied to obtain a definite diagnosis.
Both these tests are invasive and have a small risk of causing a miscarriage. A new test that has been developed uses only a blood sample from the mother. This is a non-invasive prenatal testing technique though it is more expensive to administer. A mid-pregnancy scan at 18 to 21 weeks will also throw up any physical abnormalities that the fetus has. These are called congenital anomalies and often signal the presence of a serious disorder.
The Decision Post Diagnosis
Should the baby be diagnosed with Edward's Syndrome the doctor will suggest ending the pregnancy, as it is a severe disorder which has no cure. This can be an emotionally charged time for the pregnant mother and the family. Counselling is recommended as having a support system is crucial to dealing with this situation.
If the mother chooses to continue the pregnancy, there is a fifty percent chance that the baby will be stillborn. Even if it is a live birth a number of medical complications may be expected. Baby girls have a higher survival rate than baby boys. Most of the time the baby will be admitted to the Neonatal Intensive Care Unit as the complications require a lot of critical care.
Should the baby survive the first month, the family may be able to take the baby home from the hospital. Less than 10% of the babies survive to celebrate their first birthday. The caregivers need to be mentally prepared for the eventual death of the child.